Users wish to have a broad range of telecommunication services with which to communicate with others and to efficiently exchange information. One telecommunication service, commonly known as a “one-number service,” assigns a single local telephone number to a user or subscriber. Others may communicate with the subscriber via land line telephones (such as a telephone at work and another at home), a cell phone, a one- or two-way pager, facsimile machine, and a host of other telecommunications services and devices by employing only the single number. A telecommunications server and switching system receives incoming calls to the subscriber's number, and based on the stored subscriber profile, determines how to treat the incoming call (such as forward the call to the user's cell phone, record a voice mail message, forward the call to the subscriber's secretary's telephone, etc.). Details regarding such one-number service may be found in, for example, U.S. Pat. No. 5,752,191, entitled “Telephone Control System Which Connects a Caller With a Subscriber at a Telephone Address,” U.S. Pat. No. 5,610,970, entitled “Telephone System With Scheduled Handling of Calls,” and U.S. Pat. No. 5,673,299, entitled “Adjunct Controller for a Telephone System”.
Such one-number services employ systems that are either centralized or distributed. With distributed systems, a separate telecommunications server is located in each local calling region in which the one-number service is to be provided. Unfortunately, such telecommunications servers are expensive. As a result, many one-number service providers employ centralized systems having one or more central telecommunications servers, and all incoming calls are forwarded to this central server. To provide subscribers with local telephone numbers in each region in which the one-number service is to be provided, separate channel service units (“CSU”) are located in each of such regions. Each regional CSU typically receives as input several T-1 lines to handle current and future estimated subscribers for the region. Each T-1 line may be associated with typically 500 to 1,000 local telephone numbers sold to subscribers by the service provider under the one-number service. Each CSU is then connected to a peer CSU co-located with the central server over one or more T-3 trunks or similar links. Each regional-central CSU pair includes a cross-connect switching function (among other circuitry) to route incoming calls from the T-1 lines to the central server over the leased T-3 trunk.
In operation, a caller places a call to a subscriber's one-number where, in this example, the subscriber and caller are located in a local region distant from the central server. The caller's call is routed by the regional phone company to the CSU in the region, which transparently routes the call over the T-3 trunk via the central CSU to the central server. The central server, in turn, determines the location of the subscriber, and places a long distance call to the subscriber in the subscriber's current region (the same region in this example), to thereby connect the call between the caller and the subscriber.
Unfortunately, the service provider must establish a CSU in every region in which the service provider wishes to provide service, and enter into service agreements with local exchange carriers (“LEC”) to lease a desired number of T-1 lines for the anticipated number of subscribers that may request the one-number service. Furthermore, the service provider must also enter into a service agreement with a back-haul carrier (such as a long distance telecommunications provider like Sprint or AT&T) to lease one or more T-3 trunks that connect the CSU with the central server. The T-1 lines are expensive and the T-3 trunks considerably more so. Furthermore, calls over T-3 trunks are distance and volume sensitive, i.e., the back-haul or long distance carriers charge by the mile and by the bandwidth. Thus, the service provider must pay for each long distance call between the originating CSU and the central server, and for each long distance call between the central server and the subscriber, such as to the CSU in the subscriber's region. At times, the caller and subscriber may be in the same region, or in different regions within a single LEC or regional Bell operating company (“RBOC”).
Another problem is that the service provider must provide redundancy in its network for fault tolerance and to ensure that continuous service is provided to each subscriber. Thus, the service provider may be required to establish more than one CSU within a region, more than one backhaul facility (T3 trunk for example) and/or call advance agreements with the local service providers. This duplicity of CSU pairs and of the leased capacity to interconnect them results in very high costs especially when a remote market is in an early stage of establishment and call volumes are relatively low. In the event of a failure of the CSU's in either the central or regional locations or of the leased capacity interconnecting them, call advance routing will require additional cost in central site ports and long distance charges. The call advance agreements require the regional phone company to advance calls to the central site using long distance call routing in the event that calls cannot be completed to the regional CSU T1 ports. If a failure occurs, some one-number services may not be provided because original dialed number (“ODN”) and calling line identification (“CLI”) information may not be successfully passed to the central server in a call advance routing scenario. In other words, the regional phone company drops the ODN and CLI, and thus, the central server does not know to which number the incoming call was placed, or which number the incoming call was from. Thus, callers may be required to reenter their phone number before the call is forwarded to the subscriber.
One method of solving some of the above problems is to create and employ a voice-over Internet protocol (IP) network. Voice-over IP networks may avoid the need to lease expensive T-3 trunks and pay long distance rates in order for calls to be routed by the service provider. Unfortunately, voice-over IP networks cannot use the Internet, but instead must employ a dedicated network, supporting the required protocols and quality of service (“QOS”) controls, to provide reliable and acceptable service. As result, a premium price must be paid to implement voice-over IP to get from one gateway to another. The network must be defined and implemented before providing services to subscribers. Again, the service provider must forecast the number of subscribers to be managed within a region, and must build a network to achieve the future anticipated capacity.
In the drawings, the same reference numbers identify identical or substantially similar elements or steps. To easily identify the discussion of any particular element or step, the most significant digit or digits in a reference number refer to the Figure number in which that element is first introduced (e.g., block 103 is first introduced and discussed with respect to FIG. 1).
The headings provided herein are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.